Determinación del contenido en polifenoles en uva de mesa mediante tecnología NIRS.

Phenolic compounds of red grape come from its skin. Polyfhenols are important for the physiology of grapes since they contribute to the resistance of insects and microorganisms and help to preserve grapes integrity due to their continue exposure to environment stresses including ultraviolet radiation and relatively high temperatures. Polyphenols are much related to the organoleptic properties of table grapes. In general, the techniques used to determine these compounds are usually destructive being the more commonly used the refractometer and colorimetry or the use of high performance liquid chromatography (HPLC). Near infrared (NIR) spectroscopy is a non-destructive method able to determine polyphenolic compounds. In this research, NIR spectroscopy was used to measure the polyphenol content in table grape of ‘Crimson’ variety produced in ‘Herdade Vale da Rosa’ from the Ferreira do Alentejo area located at the south of Portugal. These table grapes were harvested in September 2010 using HPLC as a reference method. In addition, their Brix content, colour and pulp and skin weight was determined. The data obtained was analysed with Unscrambled software in order to find a model capable of predicting the content of polyphenols, Brix, colour and skin. The different models obtained have allowed us predicting with a r value between 0.76 and 0.96

Difusión de la humedad y cinética del secado de judías: comparación de la validez del modelo de difusión líquida, incluyendo y excluyendo la pérdida de volumen

El objetivo de este trabajo fue ajustar el modelo de difusión líquida para predecir las pérdidas de volumen de grano en el secado de judía (Phaseolus vulgaris L.). Se recolectaron granos de judía con una humedad del 0,92 y se sometieron a un proceso de secado, bajo condiciones controladas, a diferentes temperaturas entre 25 y 55°C y humedades relativas entre 20 y 75%. El volumen de cada grano, considerado como una esfera, fue obtenido utilizando como diámetro el promedio de las tres diagonales principales durante el proceso del secado. Las pérdidas de volumen de grano se determinaron por la relación entre el contenido de agua inicial y final. A partir de los resultados obtenidos, se concluye que el modelo de difusión representa satisfactoriamente la cinética del secado de la judía, y que tiene en cuenta las pérdidas de volumen del grano. El coeficiente de difusión, con valores comprendidos entre 10,8 × 10(-10) y 67,0 × 10(-10) m(2) s(-1), aumenta con la temperatura. La variación del coeficiente de difusión con la temperatura puede ser descrita por la expresión de Arrhenius, con una energía de activación de 40,08 kJ mol(-1).The aim of this work was to compare the results of the liquid diffusion model with respect to bean (Phaseolus vulgaris L.) drying when taking into account or neglecting grain shrinkage. Bean grains were harvested with a moisture content of 0.92 kg water/kg dry matter and dried at air temperatures of 25-55 degrees C and relative humidities of 20-75%. The volume of each grain, understood as a sphere, was determined several times over the drying process, taking the diameter to be the mean length of the three orthogonal axes. Grain shrinkage was determined by examining the relationships between the volume associated with each moisture content and the initial volume. The results show that the liquid diffusion model describes the drying kinetics of beans satisfactorily, and that grain shrinkage can be ignored. The diffusion coefficient increases with air temperature, with values ranging between 10.8 x 10(-10) and 67.0 x 10(-10) m(2) s(-1). This is described by the Arrhenius equation, with an activation energy of 40.08 kJ mol(-1)

Difusión de la humedad y cinética del secado de judías: comparación de la validez del modelo de difusión líquida, incluyendo y excluyendo la pérdida de volumen

The aim of this work was to compare the results of the liquid diffusion model with respect to bean (Phaseolus vulgaris L.) drying when taking into account or neglecting grain shrinkage. Bean grains were harvested with a moisture content of 0.92 kg water/kg dry matter and dried at air temperatures of 25-55 deg C and relative humidities of 20-75%. The volume of each grain, understood as a sphere, was determined several times over the drying process, taking the diameter to be the mean length of the three orthogonal axes. Grain shrinkage was determined by examining the relationships between the volume associated with each moisture content and the initial volume. The results show that the liquid diffusion model describes the drying kinetics of beans satisfactorily, and that grain shrinkage can be ignored. The diffusion coefficient increases with air temperature, with values ranging between 10.8 x 10-10 and 67.0 x 10-10 square m sE-1. This is described by the Arrhenius equation, with an activation energy of 40.08 kJ molE-1.El objetivo de este trabajo fue ajustar el modelo de difusión líquida para predecir las pérdidas de volumen de grano en el secado de judía (Phaseolus vulgaris L.). Se recolectaron granos de judía con una humedad del 0,92 y se sometieron a un proceso de secado, bajo condiciones controladas, a diferentes temperaturas entre 25 y 55 grados C y humedades relativas entre 20 y 75%. El volumen de cada grano, considerado como una esfera, fue obtenido utilizando como diámetro el promedio de las tres diagonales principales durante el proceso del secado. Las pérdidas de volumen de grano se determinaron por la relación entre el contenido de agua inicial y final. A partir de los resultados obtenidos, se concluye que el modelo de difusión representa satisfactoriamente la cinética del secado de la judía, y que tiene en cuenta las pérdidas de volumen del grano. El coeficiente de difusión, con valores comprendidos entre 10,8 x 10-10 y 67,0 x 10-10 m cuadrados sE-1, aumenta con la temperatura. La variación del coeficiente de difusión con la temperatura puede ser descrita por la expresión de Arrhenius, con una energía de activación de 40,08 kJ molE-1

Potential of NIRS Technology for the Determination of Cannabinoid Content in Industrial Hemp (<i>Cannabis sativa</i> L.)

Industrial hemp (Cannabis sativa L.) is a plant native to Asia, and is considered to be a primary source of food, textile fiber, and medicines. It is characterized by containing minimal concentrations of delta-9 tetrahydrocannabidol (THC), which is the main psychoactive chemical component, and cannabidiol (CBD), a non-psychoactive substance. In most European countries, the maximum concentration legally allowed for cultivation is 0.2% of THC, and it is currently under debate whether to increase this level to 0.3%. Moreover, in many countries its production is being regularized and legalized, increasing the need for a rapid analysis method. The present work evaluated the cannabinoid content in hemp (Cannabis sativa L.) using near infrared spectroscopy (NIRS) technology in combination with chemometric techniques. For this, several samples of the Kompolti variety were analyzed. Samples were dried and ground, and the content of total THC (%) and total CBD (%) was determined by high performance liquid chromatography (HPLC) with a diode array detector as reference measurements, and then the spectra were collected by NIRS. Principal component analysis and partial least square regression models were developed. Good coefficients of determination of cross-validation of 0.77 for THC and CBD, and a ratio of prediction to deviation >2 for total THC and CBD, were achieved. The results obtained show that NIRS technology has potential for the quantitative determination of cannabinoids. Therefore, this analytical method would allow a simpler, more robust, precise, and sustainable estimation than the current HPLC approach